1. Field of the Invention
The field of this invention relates to protective barriers used in construction. More specifically this invention relates to protective barriers used for protecting waterproof surface or coverings on below ground level structures. Such protective barriers prevent damage to the waterproof coating or surface.
2. Related Art
There are many related art water devices for covering or protecting surfaces from water penetration. These include waterproof coverings and coatings. Similarly there are numerous protective courses which are applied over the waterproof surface to protect it from damage by earth movement or rocks and debris on backfill. The most common of these is a polystyrene foam board covering which is inserted between the earth fill and the waterproof surface. However, these foam board coverings are inadequate as they deteriorate over time and are often damaged during installation, backfill and on earth movement allowing direct contact with the waterproofing surface.
Several other methods for protection of the waterproofing course are shown in the related art. These include ROBERTS (U.S. Pat. No. 4,735,838) wherein a membrane for waterproofing the building component includes a thin plastic strip in the range of 3 mils to 10 mils thick (5 mils is preferred), having an asphalt-elastomer blend having a thickness of about 30 to 100 mils thick (the commercial embodiment is about 55 mils thick) to cause the strip to adhere to the surface in question and provide the primary waterproofing. The plastic covering is primarily for the purpose of carrying the waterproof coating and is inadequate to prevent penetration of rocks and other debris. In addition,when such strips are applied they are unwieldy to handle, not unlike hanging wall paper, accordingly, they must be applied in relatively narrow strips. This results in multiple adhesive joints as discussed in ROBERTS. More joints provide more areas for failure. Finally once such sheets are applied they have a tendency to slide out of position either on installation of additional sheets or during backfill. As the thickness of the plastic sheet increases there is a likelihood of slippage simply due to gravity. That is likely why a thin 5 mil sheet is preferred.
JACOBSON (U.S. Pat. No. 4,917,537) shows a multiple panel lining system which has very short panels having an open mesh network supported by cables mounted on anchors. In this embodiment, the panels are draped over the cable to form an inner layer and an outer layer. First the inner layer and then the outer layer are then sprayed with the waterproofing sealant. No backfill or contact with earth or rocks is anticipated by this invention. Accordingly, no protective layer is provided and the panels are simply place holders for the sealant material which prevents leakage. Again many joints are provided which result in many potential points of failure.
MEYNARD (U.S. Pat. No. 4,343,847) teaches a limited slip sheet invention, which includes multiple sheets in the sealing adhesive, each of which are perforated to allow the sealing material to pass through the sheets. The entire assemblage is supported by a carrier. This provides an overall waterproof sandwich in which the two inner perforated layers may slide relative to one another in the event of cracking in the surface to be protected. The entire assembly is considered to be the waterproofing surface. In fact, the outer carrier sheet as well as the slip sheets becomes perforated by the hot adhesive which acts as the waterproof barrier during the process of manufacturing the assemblage and therefore the adhesive is exposed directly to earth movement, rocks and other potentially penetrating materials. The MEYNARD device appears intended for roofing.
DEROSA (U.S. Pat. No. 5,406,759) does not describe a protective membrane as such but teaches the measurement of the degree of debris penetration by emulating stone impacts in backfill situations. The patent discusses, but does not disclose, the use of four layer laminate. The patent describes the falling dart test procedure. These four layer structures comprise a carrier film and a waterproof laminate one applied over the other to form a first waterproof laminate, a first carrier, a second waterproof laminate and a second carrier. The inner carrier film has a thickness of 2 to 15 mils (disclosed in the preferred test environment as 7 mils) and the outer carrier film has a thickness of at least 0.25 mils. Interestingly, DEROSA states the PVC film or polyethylene film for the outer carrier, in the test environment is of 4 mils thickness. The waterproof laminate is a rubber bitumen composition having a thickness of 10 to 50 mils (disclosed in the preferred test environment as 25 mils). Multiple layers of the rubber bitumen are provided for such protection the carrier film has a Young's modulus of at least 200,000 PSI and preferably comprises poly(ethylene terephthalate). The DEROSA patent teaches that the inner layer between the two layers of waterproofing rubber or adhesive material provides the impact resistant quality of the combination which has a synergistic relationship when used in this specific combination and composition.
The above devices are either ineffective to protect the waterproof layer when applied, or the waterproof layer itself is a complex layering of materials which is difficult to install, expensive to make in material and manufacturing costs and expensive to use due to installation costs. Flexible sheets often form throats or gaps at the top thereof where they have pulled away from the surface to be protected during installation or during backfill. Rocks and debris enter these areas between the protective course and the wall and result in future damage and failure.